Rock drill



W. A. SMITH.

ROCK DRILL.

APPLICATION FILED AUG. 13' 1920.

1,414,225 Patented Apr. 25, 1922.

II'N'VENTOR T all whom it may COW/067%.

UNITED STATES PATENT,QFFIQIEB.

WILLIAM A. SMITH, PHILLIPSBURGQNEW JERSEY, Assrenon T0 INGEnsoL -itAN'n COMPANY, or JERSEY CITY, NEW JERSEY, A coItroRA'r oN OFNEWIERSEY,

oon DRILL.

I Be it known that 1, WILLIAM AKSMYITH, a citizen of the United States, and a resident of Phillipsburg, county of Wa'rrenand State 'of New JerseyQhave invented certain new and useful Improvements in Rock Drills, of which the following is a specification.

This invention "relates tofluid actuated rock drills of the hammer type, but -more particularly to a machine having a double V end ed. differential reversible piston operated in 'a cylinder provided with a fluctuating pressure chamber at the rear of the'rearwardly extending piston shank. Fluid pressure is intermittently supplied to and ex-v hausted from the main bore of the'cylinoler in front of and behind the'main piston head and the primary objects of the present invention are to-secure a long back travel for the piston and a late cut-off onthe forward stroke, thus producing a long admission of fluid pressure against the rear or forwardly driving pressure surface of'the main piston head. I accomplish theseo'and other desir- 2 5 ableobjects primarily by 'means of a valve and a forward admission port andanother admission port rearward of said forward admission port,for supplylng fluid pressure behind the main piston head, communication 370 between the forwardand rearward admis 9 P ssag e ding o a d Po being controlled bycsaid valve 3' T all of the ends'the invention consists of the combinations of elementsand ar- I I 3:5 rangement of parts hereinaftenfully de-- scribed and claimed and shown in the ac- I companying drawings, inwhich-f Figures 1 and 2 are diagrammatic longitudinal sectional elevations o f a rock drill J :10, embodying the invention showing thepis'ton Z vhammer. in two' different positions.

L'Referring to the drawi jgsn A represents thecylinder of rock drill having the chuck B through which the drill steel C is inserted] 15 in the ,usual manner in position tor eceive the impact blows' of the revers ble rec procating piston hammer which" comprisesthe .v main piston head D having the forwardly iitar a d y ex endi a -ks 0r Xtm 5 ism E and F area wit the r duce necks e and r The mainpiston head D reciprocates with .in the larger bore Joof the cylinder and the cy der is pr i d. withb p'kllc'y de r ra i b k ee K a re L of chipped;

The cylinder provided with a suitable arrangement of the piston and the rearwardly acting prestermittent pressure.

usual exhaust port; V over-run by the piston head in each direction of'its 'travelf "If n c fi at o e 'r e Patented A r; 25'; 1922. Application'filed ni us'cis 1920. Seria1-No 403 i 352.

smaller diameter to receive the piston shank Y F. The forward portion'of the cylinder'is alsoprovided with the reduced, bore-L" to receive the forward pi'ston shank or exten- -j sion E and the reducedbores L and L in this instance are thesamejdiameter and the piston'shanks E and]? are of equal diame ters so that the piston is'r'evers'ible iii the c l nder'and maybe turned end for end as deslred n case the striking-fend becomes A and the back Learn a;

portsand passages partly controlled b the pistonand partly controlled by a valve for distributing fluid pressure to different portions of the] cylinder" for actuating-{the Piston; I I v r 'Actuating fluid such as airunder pressure is admitted at theinlet portiP controlled by the usual throttlevalve' QQ. Thechtmberf'li" at the rear of the'backhead K is under fiuctu-fl ating'pressure in accordance with this inven tionso that pressure is intermittently exerted {on the pressure surfacelSfof'the rearwardly extending piston'sha'nk The "pressure is.

also intermittently supplied in, front' of and behind the main piston head D so that both the forwardly acting pressuresurfaces 'of sure surface of the piston are s'ub'j'ect to in Fluid Pressure is supplied to and exhaust 7 ed from the fluctuating pressure {chamber R in theback head. by means-of the passage T 9 leading from the said chamber R'to aport:

U in the rear ofrthe-main-cylinder bore, wvhich port is controlled by the mainfpiston headD. Thecylinder is provided with the Y The supply "if flu d pressure to the'lirear end of the 'n aincylinder bore J behind the main piston head .is controlled partly "by the shoulder'W of the piston "shank F and which this control is effected enables me to take advantage of, the full power of areversopensinto the smallerrearward borle-Ll'of v the cylinder casing and communicates with the V ve hwbs fl zlpit h valve Q by'ineans 5 ioo partly Joy the valve O," and the manner in' of the forward admission passage 6.."A11- otherr'earwarc admission port rkconmnrnicates with the valve chamber Z) by means of the rearward admission passage and also communicates with the inlet P by means of the passage 7. t

The valve G may be constructed in any suitable manner but in this instance is pro vided with the front head 9 and the rear head It connected by areduced neck and the function of this valve is to control communication between the forward;admission passage cand the rearward admission passage ej inorder to produce a late admission of fluid pressure against the rear pressure surface ofthe main headD on the rearward A -re ..-The-.forward operative pressuresurface of the valve 0 is subject to pressure through the passage 1 leading tothe rearward end of the 7 ma n cylinder bore. The valve is thus operated Or thrown from oneposition to the other as indicated in the drawings, in accordance with the movements of the piston.

, Fluid pressure is supplied to the forward end of the main cylinder bore J through the passages 7" and s which connectthe annular groove tin the back head withthe front end of the cylinder at the port ill. The groove 2? communicates with the rearward admission port at and the forward port'u for the front shank E, and opens into-the smaller forward bore L as shown.

In the operation of the machine, let it be 7 assumedtha-t the piston is at the forward end .stroke as indicated in Figure 1.

, der is'shown exhausting through the exhaust of its stroke and is about to starton the back The cylinport V and pressure is also exhausted from the front of the valve 0 through the'passage g. The live pressure on, the rear surface 70 of the valve 0 has caused the valve to throw over or move to itsforward position as indicated in Figure 1, closing communication between the forward and rearward 5 admission passages 0 and e.

. surelto the front endof the cylinder through .,the passages rand slwhich are open. to, the supply as shown in Figure 1. As the; piston travels back; the exhaust port V to the ba'ck of'the main head D is elosed andthe admis- -si0n port'u' to the forward end ofthecylin= der is closed, but the shoulder W at the neck of the rearwardly extending piston shank plied to the re indicated in Figure 1. end-ofthe cylinder is controlled by the piston i without admitting pressure to the rearsurface of the main head D because the: forward admission passage 0 is still closed by the valve 0.

After the main head D over-runs'the c 'l inder exhaust port V the exhaustcfromithe forward end of thecylinder is open-as indicated in Figure which also opens the rear end of the valve 0 to exhaust througl i the passage 0 leadingto the front end of the cylinder; The shoulder W on the neck oof the rearward piston extension F then over runs thegrearward admission port d whi'ch admitspressure past the piston neck to the rear of the larger bore J of the cylinder, and also through the passage to the front end 9 of thevalve O, which throws the behind the mainhead forward. 7 z

.' ()wmg to the to drive the" piston fact that nopressure is supfl of the main cylinder head D when the f ifi'wardnadmission port (rf is imcovered by; the piston shoulder Viz, the piston has a substantially long, rearward stroke before the forward and rearward 'adsages c ande and supplying full pressure missionfpassages 0 and ,e are placed} in (communication. by the action of the valve 'O, and on the, other hand, the plstOIjl lS' givena late cut offon the forward stroke. be

cause cut-off does nottake place when'th'e rearward admission port d is over-run by the shoulder W but is delay'efd until-the forward admission port a is over-run by the p ston as V I/claim; Y b

1. In afluid operated'rock drlll ofthe hammer type, the combination of ayeylinder andjreversible differentialpiston subject to 7 fluctuatingpressure on one of its foi wardly acting pressure surfaces; means controlled by the piston for supplying motive fluid to the rearwardly acting pressure surface of,

the piston, a forward admission port and another admission port rearward said, forward admission port for supp'lying 'niotive fluid to the other forwardly; acting pressure surface of the piston a nd a fluid actuated valve for controlling -communication he tween forward and rearward; admission pasv sagesleading to said forward and rearward V Thepiston is. ready for .therearward 3 stroke by the admission of fluidunder presadmission ports.-

- 2.: In a, fluid operatedrock" the hammer type, the combination of a cylinder and reversibledifi'erentlal piston subject. to

another admission port rearward" of said hammer type, the combination of a cylinder and a reversible piston, means controlled by the piston for supplying motive fluid to the forward end of the cylinder, a forward ad-' mission port and another; admission port rearward of said forward admission port for supplying motive fluid to the rearward end. of the cylinder, and a fluid actuated valve for controlling communication be tween forward and rearward admission passages leading to said forward and rearward admission ports, one operative surface of said valve being subject to the fluctuating pressure in the rearward portion of the cylinder behind the piston head, and another opposed operative surface of said valve being subject to the fluctuating pressure in the front portion of the cylinder, in front of the piston head.

4. In a fluid operated rock drill of the hammer type, the combination of'a cylinder and reversible differential piston subjectto fluctuating pressure on one of itsforwardly 1 acting pressure surfaces, means controlled by the piston for supplying motivefluid to the rearwardly acting pressure surfaceof the piston, aforward admission port and another admissionport rearward of said" forward admission port for supplying mo tive fluid to the other forwardly'actingp'ressure surfaces of the piston,,and a fluid actuated valve for controlling communication between forward: and rearward. admission passages leading to sa d forward and rear- I ward admlsslon ports, one operative surface of said valve tending to open communication between said forward and rearward admission ports, being subject to thefluctuating pressure in the cylinder behind the main piston head and another opposed operative surface of said valve being subject to the fluctuating pressure in'the cylinder in front of the fmain plston head tendi-ng to close communication between said forward and rearwardadmission ports.-

In testimony whereof I have signed this specification. r 1y WILLIA A. SMITH. I 

